Real Time Location Systems (RTLSs) track objects, typically by associated tags. For individuals, a badge is used for tracking in environments such as health-care facilities, warehouses, and other areas where location is important. Personnel badges and asset tags may include Radio Frequency Identification (RFID) (passive or active), and communicate with fixed or hand-held readers.
While known tags and communication standards may hold the potential for full-scale deployment (tracking many objects in real-time), in reality, they fall short. Accuracy is impaired by the tracking environment and time delays from processing bottlenecks when realistic quantities of objects are tracked. This leads to stale, inaccurate, object location indications and even loss of tracking. Solutions are needed to support the detection performance needs of actual applications.
Although not related to detection performance, some tracking applications refer to “exclusion zones”. For example, warning systems alert authorities when individuals approach or enter forbidden areas. A particular definition is: “ . . . an exclusion zone (i.e. a geographic area that the remote tag 104 is prohibited from entering) . . . ” (U.S. Pat. No. 6,674,368). Some examples of “exclusion zones” refer strictly to a circular geographic area of a given radius, as for tracking movements of criminals on parole (U.S. Pat. Nos. 7,864,047, 8,169,316). RadarFind®'s Sentry AV sounds an alarm when a tag approaches a laundry room or exit to avoid loss of the tag. (“RadarFind Introduces Sentry AV for RTLS Alarm”, January, 2010). RadarFind® is a registered trademark of the RadarFind Corporation of Delaware.
Other applications describe “exclusion zone compliance circuits” that disable communications of Global Navigation Satellite System (GNSS) devices when they are in geographic areas such as nations prohibiting such devices (U.S. Pat. No. 8,054,181).
In a sports application, helmet-mounted infrared LEDs are tracked. Here, exclusion zones are areas of false data as would be caused by infrared (IR) interference from a light source that might be confused with the helmet-mounted infrared LEDs. Since the XYZ locations of these sources are known, data at these coordinates is not considered and ignored (U.S. 2011/0205077).
Finally, animal “exclusion zones” refers to areas around which they are prohibited. These are virtual pens to keep livestock away (U.S. Pat. No. 7,719,430).
What is needed is a system and method for improved real-time object location determination that improves detection performance and scales with the requirements of the application.